PROJECT SUMMARY Depression and metabolic syndrome (MetS) are common chronic conditions that are debilitating to individuals and costly to employers and public and private payors.1-3 Unfortunately, they are often comorbid, each making the other more severe, more difficult to manage, and more costly.4-7 This project will create MoodJaunt, a mobile app designed to fill a well-known gap8-14 in the population health management market: a lack of engaging and effective self-management programs that address both the emotional and physical wellbeing of adults managing both depression and chronic health conditions. As fully conceived, the MoodJaunt mobile app will offer an integrated approach to effect clinically significant changes in: (a) depression symptoms, (b) physical activity, (c) dietary intake, (d) weight loss, and (e) waist circumference. MoodJaunt will integrate cognitive-behavioral strategies to manage depression with a theory- based goal-attainment approach to engage patients in weight-loss activities to manage MetS. Grounded in Self Determination Theory, Motivational Interviewing, cognitive-behavioral therapy, and habit-formation research, MoodJaunt will support users' intrinsic motivations (autonomy, competence, and relatedness) to engage users in small initial health behaviors and then guide them toward clinically meaningful health habits. The Phase I functional prototype app will repurpose and adapt Jauntly, a goal-attainment platform that can be populated with goals and supportive content for a variety of self-management behaviors. Phase I content will: (a) promote behavioral activation through positive physical and social activities to manage depression and (b) build physical activity toward levels that meet NHLBI obesity clinical guidelines to begin managing MetS. We will use an Agile (iterative) development and user testing process to address three challenges: (a) creating-and optimizing engagement of-an on-boarding process that includes a user self-assessment of mood level, depression symptoms, and health-related aspirations; (b) integrating the app with a wireless accelerometer device (Fitbit(R)) to supplement self-reported physical activity data; and (c) creating a data- driven engine to tailor app-generated goals, messaging, and content, based on the user's self-assessment, program-use, and accelerometer data. The Phase II project will: (a) expand app content to address physical activity and dietary behavior goals focused on weight loss and glycemic control (reduction of calories, saturated fat, and refined carbohydrates; portion control; and weight and food-intake self-monitoring); (b) integrate with additional biometric devices to promote self-tracking of behaviors against personal results; and (c) create a client dashboard with program impact metrics. The Phase I MoodJaunt prototype will be evaluated in a 28-day randomized trial (N = 110) to assess its effect on behavioral activation, depression symptoms, and physical activity. Subjects will be recruited through the Medical/EAP Services clinic at the Washington Metropolitan Area Transit Authority.